Agree with Oliver on long and unreadable method names, but nevertheless and for the sake of argument, you can achieve desired result by using the equivalency
A /\ (B \/ C) <=> (A /\ B) \/ (A /\ C)
A and (B or C) <=> (A and B) or (A and C)
So in your case it should look something like this:
findByPlan_PlanTypeInAndSetupStepIsNullOrPlan_PlanTypeInAndStepupStepIs(...)