Multiple Health Bar

So what I want to do is only show the enemies GUIBox (healthbar) when it's clicked. Then if another enemy is clicked it switches to that one.

playerTarget:

 public var playerTarget : Transform;
 function Update()
     {
         //check if the left mouse has been pressed down this frame
         if (Input.GetMouseButtonUp(0))
         {
             //empty RaycastHit object which raycast puts the hit details into
             var hit : RaycastHit;
             //ray shooting out of the camera from where the mouse is
             var ray : Ray = Camera.main.ScreenPointToRay(Input.mousePosition);
      
             if (Physics.Raycast(ray, hit))
             {
      
             if (hit.collider.gameObject.CompareTag("Enemy"))
             {
             //print out the name if the raycast hits something
      
             Debug.Log(hit.collider.name);
      
             playerTarget = hit.collider.transform;
      
             Debug.Log("PlayerTarget Successfully changed");
      
             //var pa : PlayerAttack = GetComponent("PlayerAttack");
      
             //pa.target = playerTarget;
      
             }
             else
             {
             Debug.Log(hit.collider.name + " no tag");
             }
      
           }
      
        }
      
     }

HealthMob:

 using UnityEngine;
 using System.Collections;
 
 public class healthMob2: MonoBehaviour {
     public int maxHealth = 100;
     public int curHealth = 100;
     public float healthBarLength;
     // Use this for initialization
     void Start () {
     healthBarLength = Screen.width / 2;
     }
 
     // Update is called once per frame
     void Update () {
     AdjustCurrentHealth(0);
     }  
 
 void die() {
         Destroy(gameObject);
     }   
 
 void OnGUI()
  {
         GUI.Box(new Rect(10, 40, healthBarLength, 20), curHealth+ "/" + maxHealth);
         GUI.Label(new Rect((Screen.width) + 10, 40, healthBarLength, 20), "Allie");
     }
     public void AdjustCurrentHealth(int adj) {
         curHealth += adj;
 
         if(curHealth < 0)
         curHealth = 0;
         if(curHealth == 0)
         die();
 
         if(curHealth > maxHealth)
             curHealth = maxHealth;
         if(maxHealth < 1)
             maxHealth = 1;
 
         healthBarLength = (Screen.width / 2) * (curHealth / (float)maxHealth);
     }
 }