Problem With CSing

So, I have a problem. When my lane opponent stands directly on top of his minions, I can't autoattack them. How am I supposed to cs when this happens?

I can harass my opponent, but there are some cases where I know he's just going to heal it up (trynd, zac, etc) and I'd rather have the cs than harass him. But I can't click on the minions. How do I deal with this?

Edit for context: I'm bruiser karma top, he's trynd. He just eats my harass.