i found a simple solution 
one this code:
$fields = $this->extraFields['vendor']['FIELD_COLUMN_NAME'];
echo $this->fieldsClass->getFieldName($documents);
$onWhat = 'onchange';
if($documents->field_type == 'radio')
$onWhat = 'onclick';
$documents->table_name = 'vendor'; //$this->form_type; //'register';
if(isset($this->element->$fieldName))
$value = $this->element->$fieldName;
else
$value = $this->vendorFields->$fieldName;
echo $this->fieldsClass->display(
$documents,
$value,
'data[vendor][FIELD_COLUMN_NAME]',
false,
' ' . $onWhat . '="hikashopToggleFields(this.value,\''.'FIELD_COLUMN_NAME'.'\',\''.'vendor'.'\',0,\'hikamarket_\');"',
false,
$this->extraFields['vendor'],
$this->element);
and simpel than this cod:
just copy foreach function and add if after that for show just your specifice custom fields:
foreach($this->extraFields['vendor'] as $fieldName => $oneExtraField) {
if($fieldName!='documents' & $fieldName!='paypaldoc') continue;