How to do it...

1. Define a view of type kanban:

<record id="kanban_all_customers" model="ir.ui.view"> 
    <field name="model">res.partner</field> 
    <field name="arch" type="xml"> 
        <kanban> 

2. List the fields you'll use in your view:

    <field name="name" /> 
    <field name="supplier" /> 
    <field name="customer" />

3. Do some design:

   <templates> 
       <t t-name="kanban-box"> 
           <div class="oe_kanban_card"> 
                <a type="open"> 
                    <field name="name" /> 
                </a> 
                    <t t-if="record.supplier.raw_value or  
                     record.customer.raw_value"> 
                     is 
                     <t t-if="record.customer.raw_value"> 
                     a customer 
                     <t t-if="record.supplier.raw_value"> and </t> 
                     </t> 
                     <t t-if="record.supplier.raw_value"> 
                     a supplier 
                     </t> 
                    </t> 
               </div> 
            </t> 
     </templates> 

4. Close all the tags:

        </kanban> 
    </field> 
</record> 

5. Add this view to one of your actions. This is left as an exercise for the reader.