thanks for the answer and feedback. on the other hand(which is in my case) if someone want to remove just specific suggested fields the code can be rewritten like this:

@api.model
    def fields_get(self, allfields=None, attributes=None):
        res = super().fields_get(allfields, attributes=attributes)
        fields_to_remove_from_custom_search = ['field_1','field_2']
        for field in fields_to_remove_from_custom_search:
            if res.get(field):
                res[field]['searchable'] = False
                res[field]['sortable'] = False
        return res