How to make a mesh renderer invisible past a certain point

So, I'm working on an fast paced stealth game and I want to highlight the areas that the enemies can see i.e. make their trigger colliders have a mesh renderer. The problem is that I don't want to make said renderers pop trough walls and such. Basically I need to make the renderer behave like a light.
I was thinking of casting a light from each enemy and making a shader that is visible only when hit by that light, but I was wondering if there's an easier way.

 

You should use raycasts for collision checking and use the line renderer to draw the areas in which your enemy would be able to see you.

 

I'll play around with that idea tomorrow. Thanks for the response