I check and my client script have the map/reduce context

Are you confusing client script for user event?

No, I have a Map/reduce that only load and save a custom record, in that custom record I have a client script that update some fields, the problem is that if I run the MR it doesnt execute the client script on the save method

You need to use a user event script in your case.

ok thanks, so I assume I canno't execute a client script from a MR

Yup, that's right