Doing wudhu wearing najis clothes invalidates it or not?

No not at all unless the Najis clothe has Najasat which can touch Wudhu parts other wise there is no relation of Najis clothes with Wudhu. Wudhu could be invalidate if a person 1-passes wind from rear.2- using toilet either for pooping or urination 3- sound sleep 4-Fainting or unconsciousness 5- having sexual relation with his/her spouse.