Hey @sergeasmar 
Welcome to the Postman community! 
You could make use of the this technique described by @vdespa in his video:
That would allow you to create the body the in the pre-request script and use that as the payload. You can you the pm.iterationData.get('header_name') function in the dynamic request body to get those values from the data file.
There was also this from @odanylewycz that might be useful too: