tambien puedes igualar el valor del parametro a null.
Código SQL
[-]
ALTER PROCEDURE dbo.FiltersResultOrden
(@client int,
@createdDate datetime = null,
@deliverDate datetime = null,
@sendDate datetime = null)
AS
SELECT *
FROM Orden
WHERE (cliente = @client or @client = 0)
AND (fechaCreada = @createdDate or @createdDate is null)
AND (fechaEnviada = @deliverDate or @deliverDate is null)
AND (fechaEntregada = @sendDate or @sendDate is null)