Finally i got the Answer Please check and use it:

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.py Changes for purchase:

class skit_Partner(models.Model):

    _inherit = 'res.partner'

    def name_get(self):
        result = {}
        if self._context.get('view_customer', False):
            for partner in self: 
                result[partner.id] = str(partner.name) + ' _' + str(partner.supplier_code)
        else:
            for partner in self:
                    result[partner.id] = partner.name
 
        return result.items()

    @api.model
    def name_search(self, name, args=None, operator='ilike', limit=100):
        args = args or []
        recs = self.browse()
        if name:
            recs = self.search((args + ['|', ('supplier_code', 'ilike', name), ('name', 'ilike', name)]),
                               limit=limit)
        if not recs:
            recs = self.search([('name', operator, name)] + args, limit=limit)
        return recs.name_get()

.xml Changes:        
                <xpath expr="//field[@name='partner_id']" position="replace">
                    <field name="partner_id" context="{'view_customer': True}" />
                </xpath>