Alien Swarm Control with Mecanim

Hi, I'm trying to build a player controller like the Angry Bots or Alien Swarm. The LookAt script is working but when rotating is rotating the entire player object. I want only the Body ( torso ) of the player to rotate ( just like in Angry Bots or Alien Swarm ).

Do you have any ideea how to do this with Mecanim ? Because I'm using Mecanim to Animate the Player. Here is the script. I was thinking rotating the torso of the player but it doesn't work like I thought.

 using UnityEngine;
 using System.Collections;
 
 public class LookAtScript : MonoBehaviour {
 
     public float speed;
     public GameObject cursorPrefab;
     private Transform cursorObject;
     public float distanceFromCamera = 10f;
     private Animator anim;
 
     void Start ()
     {
         if (cursorPrefab) {
             cursorObject = (Instantiate (cursorPrefab) as GameObject).transform;
                 }
         anim = GetComponent<Animator>();
     }
 
     void Update()
     {
         Screen.showCursor = false;
         Screen.lockCursor = false;
 
         Vector3 pos = new Vector3(Input.mousePosition.x, Input.mousePosition.y, 0);
         Ray ray = Camera.main.ScreenPointToRay(pos);
         RaycastHit hit;
         if (Physics.Raycast(ray, out hit)) 
             {
             cursorObject.transform.position = hit.point;
             
             }
 
     }
 
 
     void FixedUpdate()
     {
         Vector3 playerPos = new Vector3(Input.mousePosition.x, Input.mousePosition.y, 0);
         Plane playPlane = new Plane(Vector3.up, transform.position);
         Ray ray = Camera.main.ScreenPointToRay(playerPos);
 
         float hitDistance = 0.0f;
 
         if (playPlane.Raycast(ray,out hitDistance)) 
         {
             Vector3 targetPoint = ray.GetPoint(hitDistance);
             //Vector3 targetRotationY = new Vector3(0f,anim.GetBoneTransform(HumanBodyBones.Chest).rotation.y,0f);
             Quaternion targetRotation = Quaternion.LookRotation(targetPoint-transform.position);
             //Quaternion targetRotation = Quaternion.LookRotation( targetPoint - transform.position);
             
             transform.rotation = Quaternion.Slerp(transform.rotation,targetRotation, speed*Time.deltaTime);
             
             //anim.GetBoneTransform(HumanBodyBones.Chest);
         }
         
     }
 
 }