To do this use Javascript, or better yet, a javascript library called j-query, that greatly facilitates the requisitions Ajax, example...
form
# Jquery #
<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script> 
# Requisição ajax #
<script src="model/ajaxCli.js"></script>
<form name="formCurl" id="env" method="post">
    <label for="inpPesquisa">Pesquise por clientes</label>
    <input type="text" placeholder="Digite o nome" name="termo" required="required">
    <input type="submit">
</form>
ajaxCli.js
$(document).ready(function(){
        $( "#env" ).submit(function( event ) {
         event.preventDefault();
         # pega os dados do formulário #
         var data = $("#env").serialize();
            $.ajax({
                type : "POST",
                # página php onde irá consultar #
                url  : "controller/clientes.php",
                data : data,
                dataType: "json",
                success : function(response){
                    # em caso de sucesso #
                    if (response.codigo == 1) {
          $('tbody').html('<tr><td>' + response.nomeCli + '</td><td>' + response.nomeCat + '</td></tr>');
                    };
                    # em caso de cliente não encontrado #
                    if (response.codigo == 0) {
          alert('Cliente não encontrado');
                    };
                }
            })
        });
    })
php clients.
<?php
   class getClientes{
    # seu método # ...
if(#sua condição#) {
      $retorno = array('codigo' => 1);
        echo json_encode($retorno);
        exit();
    }
    else {
      $retorno = array('codigo' => 0);
      echo json_encode($retorno);
      exit();
  }
   }
   $execClass = new getClientes();
   $execClass->termo = (isset($_POST['termo']) ? $_POST['termo'] : '');
   $execClass->_getClientes($execClass->termo);
?>
Basically that’s it, just study this function more. By the way, since it comes from desktop, you can change the library J-query by a more modularized, example AngularJs, more this for medium/long term projects, because the learning curve is higher
							
							
						 
If you use jQuery, just put inside the file that Ajax will call a script filling the fields NAME and CITY if they are found; if not, send an Alert.
– Sam