te falta especificar la tabla en tu WHERE idclie = '$customer', con eso no creo que tengas problemas cya
Código PHP:
<?php BEGIN__VBULLETIN__CODE__SNIPPET $sql = "SELECT clientes.idclie , clientes.nombres, opertation.deliveryday, opertation.nrodoc, opertation.status, opertation.respons, opertation.view, opertation.dateprocess FROM clientes, opertation WHERE nrodoc LIKE '$nrodoc%' OR DATE_FORMAT(deliveryday ,'%Y-%m-%d') >= '$deliveryday' and DATE_FORMAT(deliveryday ,'%Y-%m-%d') <= '$dateprocess' OR clientes.idclie = '$customer' ";
cya