Only targeting the targets root of vector 3 and not colliding with its mesh

I have a player and an enemy. When the enemy spawns it is moving towards the player. When it reaches the players position (Vector 3) it stops or rotates around it. The annoying part is this is only targeting his "feet" i need i to stop if it touches any part of this players body. How can i do this?

Put a trigger around the player.

http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.OnTriggerEnter.html