try to jump the starter relay and see if it will crank over. If it does, then it should start with the key in the ignition and jumping the relay if you have to.
Also check all the connections for the positive wires all the way to the starter, including the ones on the relay.
If the post on the starter relay is loose, then I would change the relay. I have one that has a loose post and needs to be changed on the one that we are rewiring... A loose post will do that.
when you hear it click, it's a low battery or loose connection where it can't get enough power across...