<p>Whenever it start printing the extruder starts clicking, I tried adjusting the voltage with no luck, it's still clicking. And it doesn't extrude a lot of plastic sometimes it even stops extruding but the extruder is still turning. Can someone help?</p>

The clicking you are hearing is either the stepper motor skipping steps or the hobbed gear losing grip on the filament.
Either way, it means that the filament opposes an unusually high resistence to be pushed forward.
A key information to be able to diagnose your problem is whether the clicking is on the firsts couple of layers or throughout the print.
If it is only for the first 1-3 layers the problem is likely to be the printing bed too high
(or deformed), so that the nozzle touches it and the bed acts a "lid" on the nozzle preventing the molten plastic to get out.  If this is the case, adjust the printing bed to be flat and level (and the nozzle at the right height when homed on the Z axis.
If the problem persists throughout the full print
the problem is likely to be related to one of the following:
the extruder not managing to get a firm grip
on the filament (worn teeth, slack spring, ...)
the stepper motor being underpowered
(this seems not to be your case, given that you have already adjusted the voltage)
a clog, adhesion, or restriction in either the bowden tube or the extruder
, for which the best solution is disassemble, inspect and clean (eventually changing the bowden tube if it has been deformed).