Usually you just patch the covering with the same material. That might be difficult if you don't know what material was originally used. If you don't know which covering was used, you may have difficulty in matching color and with a different temperature range bonding it and shrinking it tight.

For very small patches you can use 3M Plastic tape which they call decorating and repair tape. It comes in a few colors, but also clear which is what I use. It comes in rolls at 1/2" and 1" wide.