Currently if you want to be able to enact cheats such as unlimited health, unlimited ammo, unlimited armor, no reload, no weapon overheat, unlimited slow motion, improved accuracy, increased sprint speed, unlimited sprint, hover mode, no clipping mode and teleport then you will have to download a trainer.
Trainers are standalone programs which you download and then run alongside the game. They are written to intercept and alter the memory addresses of games that are running in the background and they can include features that were never programmed by the developers. They generally include hotkeys to activate the cheats in game. If you are going to download a trainer then make sure to check it is virus free before using. You will find that you have to keep the trainer program running the whole time you want to use the cheats and you will need to make sure you have the correct version of the game for that particular trainer or it probably won’t work.