Here's my problem with 'metamagic that lets me partial shift': it's going to likely very swiftly allow the character to gain powers in 'human form' that he didn't pay for. Improved Reflexes (because he gets them in his animal form), a lethal/claw attack, night vision, boosted attributes, whatever.
If the character already has all the powers he might gain by 'partial-shifting', then it's a matter of style, and should cost a small amount. If the character is looking to gain all those powers via that 'partial-shifting', whether that's enhanced vision, claws, etc. then he should pay a cost commesurate with the powers he's theorizing he could have.
In short, if he wants a 'crinos' form - which, please note, is purely a creation of Hollywood and White Wolf - then his GM would best see whether he has the powers already, and if not, then perhaps he takes the geas penalty of 'must partially shift' and call it done.