Microsoft Access - How do you search a table from a form with a checkbox on a multiple value field

After a long hiatus from Access I am back trying to develop a proof of concept DB and have been racking my brain all morning. Here's my DB layout and what I need to do.

I have a column in a tabel which has multiple values separated by a comma (ie, a, b, c, d, e, f, g)

I have the need from the customer to be able to search that column from a form with a checkbox and they may only select b, d

How can I have the checkbox on the form, search the column in the table and only return b and d?

Thanks.

If you've just started the database, it will be easier in the long run to change the schema and break it into two tables to eliminate the multi-value field.  Once you do that, standard SQL will work.