Accessing Custom Field from API


I am trying to access the item doctype through ERPNext’s API

$client = new FrappeClient();
			$result = $client->search(
							"Item",array(),array('item_name','description','_erp_number','item_code',),0,1000	// updated 5.13.21 item_name from name				

This is working fine, however I am trying to also access a field I created as a Custom Field:

When I try to add ‘short_description’ in the code above, it doesn’t work.

How can I access the custom field that is tied to the Item doctype?

Thank you.