Filter a List by Character - List of Columns

Hi,

I'm creating a list of all Columns in my query. I would like to filter this list to only show Columns that contain a particular character in the Column Header name.

I've able to get a list of all Columns using the following:

= Table.ColumnNames(#"Trim Text and Join to Last Split Step")

I want to filter my list to only show fields that contain ".". In the following step, I'm able to filter the list to only show fields with an extact match:

= List.Select(Table.ColumnNames(#"Trim Text and Join to Last Split Step"), each _ = "Campaign.Campaign")

But I want to be able to use Contains somewhere here to I can return more fields.

Any ideas on how I can achieve this in one step?

Thanks,

Mark