Someone just asked me the very same question …
All you can do is COMMUNICATE your needs and desires with him and express how much they turn you on.
A good partner will communicate his thoughts about it and may make an attempt to become involved in your fetish. However, you have to be truly ready to understand if your partner does not share your fetishes (needs and desires).
I have known a couple or two where one partner was vanilla and the other into BDSM/fisting. Their compromise was to allow the kinky partner to express his kink with someone in the BDSM community. The key is that they discuss everything without judgment.
So … to summarize … and this is really important … COMMUNICATE! it is the key for EVERY relationship in your life.