Custom Query Help

Hi Guys,
I’m trying to create a custom query to only return meetings that have the “bus_line” or “train_line” field values non empty.
Now that we have meetings that are returning to meet face to face we were going to use these fields for the “meeting and facility restrictions” information.

I have tried the following without luck:

[bmlt_tabs custom_query=”&bus_lines not empty”]
[bmlt_tabs custom_query=”&bus_lines!=””]
[bmlt_tabs custom_query=”&bus_lines not like (”)”]

Any ideas?
Thank you!