How to use operator “in” with MDX in SSRS?

I'm building an ssrs report with this MDX query:

SELECT NON EMPTY { ([KeyWords Dim].[Keywords].[Keyword].ALLMEMBERS * 
[Ad Dim].[Countries].[Countries].ALLMEMBERS * 
[Creative Dim].[Creatives].[Title].ALLMEMBERS ) }  ON ROWS,
[Measures].[Clicks] ON COLUMNS
FROM [CubeName]
WHERE ([Time Dim].[Day ID].&[20140701]:[Time Dim].[Day ID].&[20140701])

I want to add another where clause to get only result for specific countries, something like that:

Where [Getways Dim].[Countries].[Countries].ALLMEMBERS IN ([Getways Dim].[Country].[Countries].&["Germany"],[Getways Dim].[Country].[Countries].&["US"]...)

How to do the "IN" part?

(Eventually i want to show the countries to be multi-value parameter which i already created) 

Thanks