field_access.php

/**
 * Implements hook_field_access().
 * Check if user has access for the field.
 */
function MYMODULE_field_access($op, $field, $entity_type, $entity, $account) {
  if ($entity_type == 'user') {
    switch ($op) {
      case 'view':
        global $user;
        // Implement you access logic here for each field.
        // $entity is user which is being viewed.
        // You will get his privacy setting for single field in $entity->data['privacy_settings'][$field['field_name']].
        // If you want, you can use the constants defined above.
        // If current user has access to field then return TRUE, else FALSE.
        break;
    }
  }
}