Find a new target when raycast triggers

I have an AI that finds a target location and walks to it then finds another, etc. This is so it can have a wandering effect. My problem I am having is that once the ray cast triggers for the AI being too close to a wall terrain, it doesn't find a new path. All it does it turn a 180 and the turns around again to continue the same path which is into a wall. I am trying to get the AI to 180 and at the same time find another path to walk, as if it were getting too close to a wall then changing direction to avoid the wall.

Any help would be greatly appreciated!

I need help with finding out what to put in my 'if' Statement where the raycast is being called.

Here is the code I am using for the AI:

 using UnityEngine;
 using System.Collections;
 
 [RequireComponent(typeof(CharacterController))]
 public class AIScript : MonoBehaviour
 {
 
 
 
     
     
     Transform _player;
 
     Transform _Raptor;
     [SerializeField]
     public float
         _moveSpeed = 5.0f;
     /*[SerializeField]
         float
                 Distance = 0.0f;*/
     [SerializeField]
     public float
         _gravity = 2.0f;
     public float _yVelocity = 0.0f;
 
 
     // Cached variables
     CharacterController _controller;
     protected Animator RaptorAnimator;
     Transform _transform;
     
     ChangeDirection _ChangeDirection;
         //Movement variables;
 
     float speed = 5f;
     float gravity = 100f;
     Vector3 moveDirection;
     Vector3 _target;
     float maxRotSpeed = 200.0f;
     float minTime = 0.1f;
     float _velocity;
     bool change;
     float range;
     bool chase = false;
     int RandomAnimation = 1;
     int OldRandomAnimation = 0;
 
     int choice = 0;
 
     
      
     
  
     RaycastHit hit;
     
     void Start()
     {
         _controller = GetComponent<CharacterController>();
         _transform = GetComponent<Transform>();
 
 
         RaptorAnimator = GetComponent<Animator> ();
         GameObject playerGameObject = GameObject.FindGameObjectWithTag ("Player");
         _player = playerGameObject.transform;
 
 
     
 
 
         range = 2f;
         _target = GetTarget();
         InvokeRepeating("NewTarget", 0.01f, 2.0f);
     }
 
 
 
     void OnTriggerStay (Collider inrange)
     {
 
         if (inrange.tag == "Player"&& _controller.isGrounded==false) 
         {
             //Debug.Log ("Not Touching");
             RaptorAnimator.SetBool ("RunDistance", true);
             _moveSpeed = 25;
             chase = true;
         }
 
 
 
     
     }
     void OnTriggerExit(Collider outofrange)
     {
         if (outofrange.tag == "Player"&& _controller.isGrounded==false) 
         {
             RaptorAnimator.SetBool ("RunDistance", false);
             _moveSpeed = 5;
             chase = false;
         }
     }
     
     void Update()
     {
         var fwd = transform.TransformDirection (Vector3.forward);
     
         Debug.DrawLine(transform.position, fwd , Color.red);
 
         if (Physics.Raycast (transform.position, fwd, out hit, 3) ) {
             //Debug.DrawLine(transform.position, fwd * 100, Color.red);
             //Debug.Log (hit);
             Debug.Log ("The line works");
 
             transform.Rotate(0,180,0);
             change = true;
             GetTarget();
 
             //Move();
         }else{
             
 
         }
 
         if(chase == false){
             if (change) _target = GetTarget();
             
             if (Vector3.Distance(_transform.position, _target) > range )
             {
                 Move();
                 RaptorAnimator.SetBool ("Idle", false);
 
             }else{
                 RaptorAnimator.SetBool ("Idle", true);
                 RandomAnimation = Random.Range(0, 10);
             //    RaptorAnimator.SetBool ("Animation Running", true);
 
                 if(RandomAnimation != OldRandomAnimation){
                 RaptorAnimator.SetInteger ("RandomAnimationIdle", RandomAnimation);
                 }else{
                 RandomAnimation =     Random.Range(0, 10);
                 }
             }
                 
 
             
             
             
 
 
         }else{
             RaptorAnimator.SetBool ("Idle", false);
             Vector3 direction = _player.position - transform.position;
             
             direction.Normalize ();
             
             Vector3 velocity = direction * _moveSpeed;
             
             
             
             
             if (!_controller.isGrounded) {
                 _yVelocity -= _gravity;
             }
             
             velocity.y = _yVelocity;
             direction.y = 0;
             transform.rotation = Quaternion.LookRotation (direction);
             _controller.Move (velocity * Time.deltaTime);
 
         }
 
     }
     
     void Move()
     {
         // Movement
         moveDirection = _transform.forward;
         moveDirection *= speed;
         moveDirection.y -= gravity * Time.deltaTime;
         _controller.Move(moveDirection * Time.deltaTime);
         //Rotation
         var newRotation = Quaternion.LookRotation(_target - _transform.position).eulerAngles;
         var angles = _transform.rotation.eulerAngles;
         _transform.rotation = Quaternion.Euler(angles.x,
                                                Mathf.SmoothDampAngle(angles.y, newRotation.y, ref _velocity, minTime, maxRotSpeed),
                                                angles.z);
     }
     
     Vector3 GetTarget()
     {
         return new Vector3(Random.Range(0, 300), 0, Random.Range(0, 300));
     }
     
     void NewTarget()
     {
 
         choice = Random.Range (0, 3);
         switch (choice)
         {
         case 0:
             change = true;
             break;
         case 1:
             change = false;
             break;
         case 2:
             _target = transform.position;
             break;
         }
     }
 }