I created a custom mobile field in res.partner (Customer) to make it as mandatory. Odoo is not allowing to check the required for base (mobile) field. 

I want to copy my custom field value to base field, so I can print and show the value in kanban view and Reports. 

1. I am using Odoo cloud version.
2. I am not using Odoo studio as well.

How to copy the custom field value to base field ???

Thanks in advance!!!! :)