How can I conditionally require a field?

I need to have an option:

If yes is checked 

Certain fields are required

If no is checked 

No fields are required

How do I set this up on my form

What you're describing can be achieved using CONDITIONS. In particular, the ENABLE / REQUIRE FIELD condition.

Complete guide: How-to-Make-a-Field-Required-Based-on-User-s-Answer

Give it a spin and let us know if you'd need more help.