If I recall correctly according to “The Art and Science of Low Carbohydrate Living" book (written by the two leading experts on very low carb) it should be 50% of calories from fat if you wish to lose weight and 75% once you have used up most of your own body fat. However, this is based on Very Low Carb, so fewer than 40g of carbs a day. With more carbs, you should be eating less fat, or ideally cut the carbs down more.
A good steak is about 20% fat by weight, therefore about 40% fat by calories, put a little butter on your grean veg and you get close enough to 50% fat by calories. (If you want more fat, add for example a cream and cheese source, or some olive oil on your side salad.) Normal (not low fat) minced beef etc is about the same, I often make my own burgers etc with a bit of cheese and green vag.
Personally, I have done Very Low Carb, without thinking about the calories and just buy my meat without trying to avoid fat, along with lots of olives etc. No ready meals etc. I am getting good results without trying to get a "correct" Fat to Protein Ratio, but I am not far from 50% the few times I have worked it out.
I also find coconut milk very useful for making curries (fish or chicken) that we eat with a selection of green veg.