Create a new user role called "client" in Wordpress.

Create New User Role Client.php

/*-----------------------------------------------*/
/* Create new Role for: Client
/*-----------------------------------------------*/
$result = add_role( 'client', __('Client' ),
 
   array(
      'read' => true, // true allows this capability
      'edit_posts' => false, // Allows user to edit their own posts
      'edit_pages' => false, // Allows user to edit pages
      'edit_others_posts' => false, // Allows user to edit others posts not just their own
      'create_posts' => false, // Allows user to create new posts
      'manage_categories' => false, // Allows user to manage post categories
      'publish_posts' => false, // Allows the user to publish, otherwise posts stays in draft mode
      'edit_themes' => false, // false denies this capability. User can’t edit your theme
      'install_plugins' => false, // User cant add new plugins
      'update_plugin' => false, // User can’t update any plugins
      'update_core' => false // user cant perform core updates
   )
);