The click is coming from a relay engaging. You probably have a dead battery. There seems to be just enough power to energize a relay but not nearly enough power to crank the engine.

Bad Main Relay?

The battery most likely is dead or the terminals are not tight enough

turn key

1996 ford taurus...I replaced the spark plugs after the car wouldn't start, because I popped one out and it cracked just taking it out and the car started. Few days later it stopped working so I replaced the battery and alternator at the same time (get a good deal from my uncle on parts). Well neither fixed the problem and I replaced the starter because it wouldn't start even with a jump. Well after replacing all of them with tested parts that are good, the car still doesn't start. It has over half a tank of gas. When I turned it wouldn't crank at all, a few clicks that slowly stopped, but some clicks by the fuse box. Any ideas what it could be? Fuses are all fine, tried switching relays but that didn't help.