Comment remplir une variable avec foreach ???

<form action="forCanton.php?step=4" method="post">
<?php
$STEP=$_GET['step'];


ECHO '<FONT SIZE="2"><input type="checkbox" name="site[]" value="JU">Jura</FONT><br>';
ECHO '<FONT SIZE="2"><input type="checkbox" name="site[]" value="JU1">Jura1</FONT><br>';
ECHO '<FONT SIZE="2"><input type="checkbox" name="site[]" value="JU2">Jura2</FONT><br>';
ECHO '<FONT SIZE="2"><input type="checkbox" name="site[]" value="JU3">Jura3</FONT><br>';
ECHO '<FONT SIZE="2"><input type="checkbox" name="site[]" value="JU4">Jura4</FONT><br>';
echo '<INPUT type="submit" value="go">';
echo '</form>';

 IF ($STEP=="4") { 
$site = $_POST['site'];
IF(!EMPTY($site)) {

foreach ($site as $choix)
  {
  echo $choix,' OR ';
  }
  
}} // fin du step 4


echo $choix;
/*
$Query5 = "SELECT * FROM 'MANIFS' WHERE CANTON = $choix" ;
$Req5 = mysqli_query($db65, $Query5);
while($data5 = mysqli_fetch_assoc($Req5)) 
    {
    $Npa = $data5['NPAMANIF'];
    $Localitemanif = $data5['LOCALITEMANIF'];
    $cantonmanif = $data5['CANTON'];
    $titremanif = $data5['TITRE'];    
    }
    
*/    
    
?>