SOAP Request to get invoices for a customer along with its custom fields

Can anyone help me with the correct SOAP request to submit in order to get all of the invoices for a particular client along with the invoices associated custom fields

So far i have the following:

 <soap:Envelope      xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"      xmlns:tns="urn:platform_2017_1.webservices.netsuite.com"      xmlns:platformMsgs="urn:messages_2017_1.platform.webservices.netsuite.com"      xmlns:platformFaults="urn:faults_2017_1.platform.webservices.netsuite.com"      xmlns:xsd="http://www.w3.org/2001/XMLSchema"      xmlns:q1="urn:sales_2017_1.transactions.webservices.netsuite.com"      xmlns:core="urn:core_2017_1.platform.webservices.netsuite.com"      xmlns:platformCommon="urn:common_2017_1.platform.webservices.netsuite.com">      <soap:Header>          <applicationInfo>              <applicationId>xxxxxxxx</applicationId>          </applicationInfo>          <passport>              <account>xxxxxxx</account>              <email>xxxxxxxx</email>              <password>xxxxxxx</password>              <role internalId="3"></role>          </passport>          <searchPreferences>              <pageSize>50</pageSize>          </searchPreferences>      </soap:Header>      <soap:Body>          <search>              <searchRecord xsi:type="q1:TransactionSearchAdvanced">                  <q1:criteria>                      <q1:basic>                          <entity operator="anyOf">                              <searchValue type="customer" externalId="CUS: xxxxxx"/>                          </entity>                          <type operator="anyOf">                              <searchValue>_invoice</searchValue>                          </type>                      </q1:basic>                  </q1:criteria>                  <q1:columns>                      <q1:basic>                          <dateCreated/>                          <entity/>                          <internalId/>                          <externalId/>                          <total/>                          <tranId/>                          <tranDate/>                          <amount/>                          <amountPaid/>                          <quantity/>                          <rate/>                          <location/>                          <otherRefNum/>                          <memo/>                          <account/>                          <department/>                      </q1:basic>                  </q1:columns>              </searchRecord>              </search>      </soap:Body>  </soap:Envelope>