Unlock doors without keys

The vehicle must be equipped with 'Keyless Entry" system. You didn't mention if your vehicle is equipped with it. If it isn't, there are 'after market' systems which you can install 'do-it-yourself', provided your door locks are electrical. If your door lock are 'manual', you cannot install a "keyless entry' system without replacing the door lock/unlock actuators & main wiring harnesses.