Sometimes just clicks when try to start

The contacts in your starter relay may be partially fouled. Each time you start your car the contacts engage each other in a slightly different way. It's possible that every now and then the portions that touch are fouled enough to prevent current flow. Jumping across the starter relay posts bypasses those contacts, so if doing so reliably turns it over every time then odds are the starter relay is bad. If not then odds are it's the starter. Of course this assumes that all of your connections are good and tight.