If your cat is currently on a kibble diet, start by offering small treats of raw food. Slowly increase the amount of raw food, while decreasing the amount of kibble. Make sure to transition to a raw food diet gradually, because a new food introduced too quickly may cause diarrhea. The transition can take 7 days or more for kitties particularly addicted to kibble, or for those with sensitive stomachs or other health issues. Note that it is important not to free feed your cat, moving it to a feeding schedule (2-3 times per day. For example, feeding in the morning and in the evening).
Alternatively, the transition can be made gradually from kibble to a wet canned food, first. Afterwards, move the kitty from wet to raw gradually. It is very important to stick to the feeding schedule during and after the transition.