It seems with nvidia-prime you cannot, but you could install bumblebee and remove nvidia-prime, then you you would have to specify witch applications to run with nvidia card.

check if you have primusrun in /usr/bin.

First you cound try updating your drivers if you have ubuntu you can most likely do it by updating your system in update manager or running 'sudo apt-get upgrade && sudo apt-get dist-upgrade' in terminal.If you dont run steam with optirun you can launch games with optirun by going in to library open games properties then set launch parameters.. and add 'optirun %command%' without quotes and at the very start before anything else, and you may have to disable ingame overlay for it to work.

Try to launch it like this
"vblank_mode=0 primusrun yourprogram"
if it works add "export vblank_mode=0" before the last line in /usr/bin/primusrun.