filter using two columns

it would probably make sense to calculate a new table to handle this. The table will have two columns, Corporate and SalesPerson :

Slicer Table =
UNION (
SELECTCOLUMNS (
FILTER( 'Table' , 'Table'[Corporate] <> BLANK() ) ,
"Source" , 'Table'[Source] ,
"Selection" , 'Table'[Corporate]
),
SELECTCOLUMNS (
FILTER ( 'Table' , 'Table'[Salesperson] <> BLANK() ) ,
"Source" , 'Table'[Source] ,
"Selection" , 'Table'[SalesPerson]
)
)
After this has been calculated, create a relationship between these tables, between the Source columns. Since this is purely for filtering the table on the person of interest, make it be Many-to-Many and have Slicer Table filter Table:

Create a slicer with the Selection column from the Slicer Table and test the functionality: