Okay, let's get something straight. Only very rarely will you be fed enough to truly carry the team by yourself. You have to realize that even though you're fed, you're only one person and you can only do so much. God forbid that the team focuses you like they're supposed to and kill you before you can do any damage. Then it's just them mopping up the rest of your team.
Let me start with an anecdote: I have a friend who is a fantastic adc. HOnestly plat level, though he's not quite there yet. He very rarely loses a lane, and if he does he makes a nice comeback mid to late game.
When he kills his turret bot lane, he will help other lanes. But he tries not to take farm, and he tries not to take kills from the mid laner IF THE MID LANER IS BEHIND.
Carrying, in many cases, merely means being fed enough to help your team to catch up to your level of damage. Giving kills to your teammates, allowing them to take a lot of farm etc etc is how you do it. Basically, if you're truly carrying, your main concern should be postponing the game until your team can reach late game when things are much more even and every person has many items.
At this point, you want to also stay focused and kill the enemy damage. In team fights, your main concern should be either peeling for your damage, or eliminating the enemy damage. That means focusing the adc, apc, or top laner. Just whoever is the biggest threat to your team. If you're fed sufficiently, you should have no difficulty in accomplishing this.
Either way I hope this helped, good luck!