Cats are carnivores - they need fresh meat to survive and thrive.
They do not require anywhere near the same amount of vegetables or plant matter as dogs, however it is commonly suggested that a cat who would eat prey animals in the wild (eg. small birds, rats, mice, rabbits, etc) would naturally take in a small amount of plant matter as a result of eating the stomach contents of that animal. Therefore, if your cat readily accepts a small amount of vegetable in their diet, then it is not going to harm them, but do ensure that the majority of their diet consists of fresh, raw meat and some bones like chicken necks or chicken frames for the more adventurous cats!
The fresh, raw meat is the most important component of a cat's diet as they need the taurine found in meat (and particularly in organ meat) for healthy eyes and eyesight.
We personally feed our cat a combination of the 'cat-specific' products by Canine Country and occasional chicken necks (she's not a huge fan of bones). We also feed her the Super White (chicken, duck, turkey, fish mince) and the same BARF products that our dogs eat which have a higher proportion of vegetables and fruit - she goes crazy for the lamb! About every 10-14 days we also give our cat and dogs some sardines for the beneficial oils and for variety.
Cats can be particularly fussy eaters and it can take some time and effort to convince them that a raw diet is better for them, but once they realise what they've been missing with that artificially constructed dehydrated kibble, they'll be meowing in demand at dinner time when they smell the fresh, natural, raw meat you're about to serve up!