In order to upload the client's image to the system, you need to create the upload image field:
Go to the "Setup".
Click on the "Custom Field ".
Mark the box for the Client Picture.
To upload the Client Image:
Go to the "Clients".
Select the Client, Click on the three dots(...).
Click on "Edit".
Upload the Image, and Click on SAVE.
Additionally, you can also upload the picture when you add a new client.