how to use 'like' in SSRS

select po_hdr.po_no, po_hdr.order_date, po_hdr.created_by, expdite_date, next_action, vendor_name, supplier_so, contact_id,
contacts.email_address, contacts.direct_phone, contacts.home_phone, contacts.phone_ext, ackn_date
from po_hdr_ud
join po_hdr on po_hdr.po_no = po_hdr_ud.po_no
join vendor on vendor.vendor_id = po_hdr.vendor_id
left join contacts on po_hdr.contact_id = contacts.id
WHERE (po_hdr.po_no = @RG_PO_NO or @RG_PO_NO is null) AND (po_hdr_ud.supplier_so LIKE @Supplier_SO or @Supplier_SO = '') AND (vendor_name like '*'+@
Supplier_Name+'*' or @Supplier_Name = '') and (po_hdr.created_by LIKE @RG_Buyer or @RG_Buyer = '')