How to add a custom field as new column to all customer overview?

v1.5.11

Hi everybody,
I would like to show more informations in the all clients overview.
Why? I created an ID-field as custom field and added it to the “client” - table. I could yet successfully print it in the invoce-templates. Now I would like to add it as an additional column which would print this custom field like e.g. “customer ID” to the “show customer” view. Making this table sortable by this custom field would make my day :wink:
How to make it real? Thanks in advance for any suggestions

With the code of this post I could successfully help me out and display the custom field in the partial_client_table.php
Somebody have an idea how to make the table sortable?