i am a bit confused on short circuit protection, i don't know how to do this, i have to use relay or MOSFET, i don't know how this circuit will work and, which is the best,
a mosfet can act like a relay.(switch--on/off)
relay has more time delay than mosfet.
but relay can switch higher current than mosfet , with less cost.
you require appropriate circuitry for mosfet to switch.
If this is only for over current protection during short and temp requirement is less than 85C then you can search for a ressetable fuse, else use a P-type FET with gate to be controlled by some over current protection circuit.
I just wanna say that using a mosfet for that case isn't such a great idea if your around radios (walkie talkies) that might turn it on if it's not properly sheildied.