The time-honored tradition of distraction is probably one of your best offensive tactics. Keep a basket of cat toys near the desk for your cat to play with. You could even set up a kitty condo or play area near your computer so that it's near you and you can keep an eye on it as it plays.  Rotate toys for added interest. Keep the cat's interest by only putting out one or two toys at a time. Try tying a string to your office door handle to provide your cat with the opportunity to bat it around. You can also try battery-operated toys. These can be particularly helpful if you need to focus on work but your cat likes a lot of play time. Every time your cat threatens to jump up on your workspace, grab the pointer and start playing laser tag across the floor. You can lead your cat away from your work area and into the ecstasy of play. There are even some automated laser toys that will occupy your cat without you needing to be an active participant. Set up a comfy space for your cat that is near your but not right next to your keyboard. Very often your cat just wants to be near you while you work or play on the computer. Indeed, the longer you're stuck there, the more it wants your attention and will be likely to put itself right in your face to get it. By placing a bed or comfy sleep spot near you as you work or play on the computer, your cat may be satisfied enough that it can see you to avoid feeling the need to attack your keyboard.  If you have a laptop, your cat may like the warmth of the computer. Try using a heated bed to keep them warm and off the keys. The comfort zone may not work with a kitten. Kittens think that everything is an invitation to play and that sleep just gets in the way. All the same, the earlier you can train your kitten to like sleeping near your workspace rather than pawing all over it, the better.

Summary:
Provide your cat with toys. Distract the cat with a laser pointer. Create a comfort zone for your cat near the workspace.