You are expected to cover the charges, fees and taxes independently
Buying a property in Spain will incur additional costs on top of the purchase price which, based on the location can range from 8% - 15%. This includes nationally-levied and local taxes, notary fees, legal fees and land registry fees.
The bank won't lend for the fees only the agreed loan to value on the property value (LTVs are 70% maximum for non-residents and 80% for residents of Spain).
You will not be able to add charges, fees and taxes to the mortgage value you are taking out. You will need separate funds for these, and a lender will consider such costs in their affordability assessments. All of the clients' contributions for the deposit and the costs have to come from savings or liquidity.